Set to Material Design 3

lib/app_theme.dart

@@ -1,11 +1,14 @@
 import 'package:flutter/material.dart';
 
 class AppTheme {
-  static ThemeData light = ThemeData(primarySwatch: Colors.indigo);
+  static ThemeData light = ThemeData(
+    colorSchemeSeed: Colors.indigo,
+    useMaterial3: true,
+  );
 
-  static ThemeData dark = ThemeData.from(
-      colorScheme: ColorScheme.fromSwatch(
-    primarySwatch: Colors.cyan,
+  static ThemeData dark = ThemeData(
+    colorSchemeSeed: Colors.indigo,
+    useMaterial3: true,
     brightness: Brightness.dark,
-  ));
+  );
 }